package com.tanhua.server.interceptor;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.tanhua.common.utils.Cache;
import org.apache.commons.codec.digest.DigestUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@Component
public class RedisCacheInterceptor implements HandlerInterceptor {

    @Value("${tanhua.cache.enable}")
    private Boolean enable;

    @Autowired
    private RedisTemplate<String,String> redisTemplate;

    private static final ObjectMapper MAPPER = new ObjectMapper();

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        if(!enable){
            return true;
        }

        //只要不满足其中一个就返回true
        if(!(handler instanceof HandlerMethod) || !((HandlerMethod) handler).hasMethodAnnotation(GetMapping.class) ||
                !((HandlerMethod) handler).hasMethodAnnotation(Cache.class)){
            return true;
        }

        String redisKey = createRedisKey(request);
        String data = redisTemplate.opsForValue().get(redisKey);
        if(StringUtils.isEmpty(data)){
            //redis中未获取到对应数据
            return true;
        }

        response.setCharacterEncoding("UTF-8");
        response.setContentType("application/json; charset=utf-8");
        response.getWriter().write(data);


        return false;
    }

    //生成redis中的key
    public static String createRedisKey(HttpServletRequest request)throws Exception{
        return "SERVER_CACHE_DATA_"+ DigestUtils.md5Hex(request.getRequestURL()+"_"+
                MAPPER.writeValueAsString(request.getParameterMap())+"_"+request.getHeader("Authorization"));
    }
}
